A. bought a private house and, having registered the ownership of it, found out that there was an unliquidated property tax liability for this property. Is A. obligated to pay off the accumulated debt if it arose before the state registration of the property right?
Yes. In case of acquisition of property subject to taxation, and in this case of a private house, if there is an outstanding liability for property tax, the new owner, i.e. A. As a buyer, it is responsible for its repayment.